It is disclosed by, for example, JP-A-2006-5836 (pages 4-7, FIGS. 2, 3, 6) that a portable information terminal is loaded with an antenna module and an IC tag, which is inductive-coupled with an antenna portion of an external reader/writer to carry out communication with it.
A portable information terminal disclosed in JP-A-2006-5836 is loaded with an antenna module 10 and a battery pack 4. Then, communication is carried out between the antenna module 10 and an external reader/writer. In order to prevent deterioration of communication performance caused by generation of an eddy current on a metal surface of the battery pack 4 under the influence of a magnetic field generated as the time of this communication, the antenna module 10 is provided with a magnetic core member 18 (magnetic sheet) in which soft magnetic powders are mixed (See FIG. 3 of JP-A-2006-5836). An opening portion 18a for accommodating a signal processing circuit section 16 is formed in the magnetic core member 18 serving as a magnetic sheet.
In a portable information terminal disclosed in JP-A-2006-5836, the magnetic core member 18 serving as a magnetic sheet reduces an eddy current on a metal surface of the battery pack 4. However, the opening portion 18a is formed in the magnetic core member 18, and an eddy current reduction effect has been already reduced.